The present invention relates to polymers, and more particularly relates to water-soluble polymers having low organic chemical impurity levels and methods to achieve the same. The present invention also relates to dry or solid water-soluble polymers and methods of making the same. The present invention further relates to the use of dry water-soluble polymers for a variety of applications.
Biological fouling is a persistent nuisance or problem in all varieties of aqueous systems. Biological fouling can have a direct adverse economic impact when it occurs in industrial process waters, for example in cooling waters, metal working fluids, or other recirculating water systems such as those used in papermaking or textile manufacture. If not controlled, biological fouling of industrial process waters can interfere with process operations, lowering process efficiency, wasting energy, plugging the water-handling system, and even degrading product quality.
Biological fouling of recreational water systems such as pools, spas, or decorative (or ornamental) water systems, (e.g., ponds or fountains), can severely detract from people's enjoyment of them. Biological fouling often results in objectionable odors. More importantly, particularly in recreational waters, biological fouling can degrade the water quality to such an extent that it becomes unfit for use and may even pose a health risk.
Sanitation waters, like industrial process waters and recreational waters, are also vulnerable to biological fouling and its associated problems. Sanitation waters include, for example, toilet water, cistern water, and sewage treatment waters. Due to the nature of the waste contained in sanitation waters, these water systems are particularly susceptible to biological fouling.
Ionene polymers have often been used to control or prevent biological fouling, including biofilm and slime formation, in aqueous systems. Advantageously, ionene polymers, or polymeric quaternary ammonium compounds (polyquats), generally do not foam excessively in water or aqueous systems, do not irritate skin, and exhibit extremely low toxicity to warm-blooded animals. These characteristics along with their ability to control or prevent biological fouling cause ionene polymers to be excellent choices for water treatment.
Ionene polymers are commonly sold and used as liquid compositions such as aqueous solutions or formulations. Solid forms, including tablets, of ionene polymers have been disclosed in U.S. Pat. Nos. 5,142,002 and 5,419,897. Other water treatment chemicals are often sold in solid forms, such as tablets or pucks. The following patents describe various solid forms of water treatment chemicals for use in a number of different aqueous systems: U.S. Pat. Nos. 4,310,434, 4,396,522, 4,477,363, 4,654,341, 4,683,072, 4,820,449, 4,876,003, 4,911,858, 4,961,872, and 5,205,955 as well as U.K. Patent No. 1,601,123, PCT Application WO 91/18510, PCT Application WO 92/13528, and European Patent Application No. 0 525 437 A1.
When making various polymers, such as water-soluble polymers, for instance, ionene polymers, some of the reactants or by-products, which are in the form of organic impurities, remain after the polymer is formed. These impurities can be detrimental when present with the polymer based on the applications for the polymer, such as in water treatment or the treatment of aqueous systems. Accordingly, there is a need to remove these various organic impurities, such as TMEDA, dioxane, epichlorohydrin, or derivatives thereof, acrylic acid, acrylamide, and the like.
In some applications solid forms provide advantages over liquid compositions. Well formulated solid forms provide increased stability and reduce exposure to chemicals, solvents, or vapors. In a solid, different ingredients may be successfully combined where such a combination in a liquid might lead to unwanted reactions and potential loss of activity. Using a solid form, a chemical composition can often be packaged and shipped in a more concentrated form than with liquid compositions. Solid forms can also reduce or eliminate concerns regarding the liquid spilling or containers breaking during shipping or handling.
At the point of use, solid forms may also offer additional advantages over liquid formulations. Solid forms provide unit dosing and a uniform delivery system reducing errors in amounts used. Solid forms of water treatment chemicals can also be formulated to provide sustained or prolonged release of chemical to the aqueous system.
As shown by the above discussion, it would be desirable to combine the biological efficacy of an ionene polymer or other polymer with the advantages of a solid formulation. Solid forms of water-soluble polymers would compliment the utility of liquid polymer formulations. Accordingly, there exists a need for solid forms of water-soluble polymers, like ionene polymers, useable in water treatment and other uses.
Generally, in the past, dry polymers have been obtained by heating the water-soluble polymer present in an aqueous solution in order to evaporate the water and thereby obtain the solid which can have a glass-like consistency. Afterwards, the solid can be reduced to powder form or other forms. Also, polymers, such as water-soluble polymers, have been formed into granules by mixing an aqueous solution of a polymer, such as an ionene polymer, with a carrier matrix, such as a salt, to form a moist mass which is then dried to form granules.
In each of these methods, enormous efforts are made to subject the wet polymer to sufficient heat in order to evaporate the water or moisture to obtain a solid. This takes enormous time and energy costs. In addition, the moisture content generally is 20% or higher, even after the product is obtained in solid form since driving off any additional moisture would be difficult or not possible for a variety of reasons. In addition, these processes do not typically remove any organic chemical impurities that may be present in the polymer.
Thus, there is a need to provide methods which can obtain dry water-soluble polymers that preferably have a low moisture or water content, and which can avoid the time consuming and/or energy costs of previous methods.
There is also a need to provide polymers having low organic chemical impurity levels and to provide methods to achieve this.